Amplitude-phase retrieval attack free image encryption based on two random masks and interference

• The nonlinearity of the cryptosystem is strengthened due to nonlinear encryption process.
• The decryption process in linear and easily implemented with the basic 4f4f optical system.
• The cryptosystem avoids the silhouette problem of the interference-based scheme elaborately.
• The cryptosystem has high immunity to the specific attack due to fewer constraints.

An amplitude-phase retrieval attack free encryption scheme is proposed by using two random masks, where one is considered as the random image and other as the public key. Initially, the random image is encrypted to two phase-only masks based on interference technique with the help of the public key. These two phase-only masks are real-valued functions and used as the encryption keys. Then, the plain image is encrypted to the ciphertext with the white noise distribution by using the phase-truncated Fourier-transform-based encoding scheme with the previous encryption keys. The encryption process is nonlinear in which no iterative calculation is involved, while the decryption process is linear which can be easily implemented with the 4f4f optical system. Moreover, less constraints makes the specific attack unusable. Simulation results are given to verify the feasibility and robustness of the proposed encryption scheme.